Calculate the energy associated with red light with a wavelength of 725 nm

Given:

Wavelength (λ) of red light = 725 nm

To determine:

Energy associated with the given wavelength

Explanation:

The relation between energy (E) and wavelength (λ) is given as-

E = hc/λ

where :  h = Planck's constant 6.626 * 10⁻³⁴ Js

             c = speed of light = 3*10⁸ m/s

E = 6.626*10⁻³⁴ Js * 3*10⁸ ms⁻¹/725*10⁻⁹ m = 2.74*10⁻¹⁹ J

Ans: Energy associated with a wavelength of 725 nm is 2.72*10⁻¹⁹ J